tree-wide: add path_simplify_alloc() and use it

path_simplify_full()/path_simplify() are changed to allow a NULL path, for
which a NULL is returned. Generally, callers have already asserted before that
the argument is nonnull. This way path_simplify_full()/path_simplify() and
path_simplify_alloc() behave consistently.

In sd-device.c, logging in device_set_syspath() is intentionally dropped: other
branches don't log.

In mount-tool.c, logging in parse_argv() is changed to log the user-specified
value, not the simplified string. In an error message, we should show the
actual argument we got, not some transformed version.

src/basic/cgroup-util.c

@@ -947,6 +947,7 @@ int cg_is_empty_recursive(const char *controller, const char *path) {
 
 int cg_split_spec(const char *spec, char **ret_controller, char **ret_path) {
         _cleanup_free_ char *controller = NULL, *path = NULL;
+        int r;
 
         assert(spec);
 
@@ -955,11 +956,9 @@ int cg_split_spec(const char *spec, char **ret_controller, char **ret_path) {
                         return -EINVAL;
 
                 if (ret_path) {
-                        path = strdup(spec);
-                        if (!path)
-                                return -ENOMEM;
-
-                        path_simplify(path);
+                        r = path_simplify_alloc(spec, &path);
+                        if (r < 0)
+                                return r;
                 }
 
         } else {
@@ -1006,22 +1005,14 @@ int cg_split_spec(const char *spec, char **ret_controller, char **ret_path) {
 
 int cg_mangle_path(const char *path, char **result) {
         _cleanup_free_ char *c = NULL, *p = NULL;
-        char *t;
         int r;
 
         assert(path);
         assert(result);
 
         /* First, check if it already is a filesystem path */
-        if (path_startswith(path, "/sys/fs/cgroup")) {
-
-                t = strdup(path);
-                if (!t)
-                        return -ENOMEM;
-
-                *result = path_simplify(t);
-                return 0;
-        }
+        if (path_startswith(path, "/sys/fs/cgroup"))
+                return path_simplify_alloc(path, result);
 
         /* Otherwise, treat it as cg spec */
         r = cg_split_spec(path, &c, &p);

src/basic/fileio.c

@@ -1110,6 +1110,7 @@ int search_and_fopen(
                 char **ret_path) {
 
         _cleanup_strv_free_ char **copy = NULL;
+        int r;
 
         assert(filename);
         assert(mode);
@@ -1123,13 +1124,9 @@ int search_and_fopen(
                         return -errno;
 
                 if (ret_path) {
-                        char *p;
-
-                        p = strdup(filename);
-                        if (!p)
-                                return -ENOMEM;
-
-                        *ret_path = path_simplify(p);
+                        r = path_simplify_alloc(filename, ret_path);
+                        if (r < 0)
+                                return r;
                 }
 
                 *ret = TAKE_PTR(f);
@@ -1152,6 +1149,7 @@ int search_and_fopen_nulstr(
                 char **ret_path) {
 
         _cleanup_strv_free_ char **s = NULL;
+        int r;
 
         if (path_is_absolute(filename)) {
                 _cleanup_fclose_ FILE *f = NULL;
@@ -1161,13 +1159,9 @@ int search_and_fopen_nulstr(
                         return -errno;
 
                 if (ret_path) {
-                        char *p;
-
-                        p = strdup(filename);
-                        if (!p)
-                                return -ENOMEM;
-
-                        *ret_path = path_simplify(p);
+                        r = path_simplify_alloc(filename, ret_path);
+                        if (r < 0)
+                                return r;
                 }
 
                 *ret = TAKE_PTR(f);

src/basic/path-util.c

@@ -132,11 +132,9 @@ int path_make_relative(const char *from, const char *to, char **ret) {
                                         return -ENOMEM;
                         } else {
                                 /* 'to' is inside of 'from'. */
-                                result = strdup(t);
-                                if (!result)
-                                        return -ENOMEM;
-
-                                path_simplify(result);
+                                r = path_simplify_alloc(t, &result);
+                                if (r < 0)
+                                        return r;
 
                                 if (!path_is_valid(result))
                                         return -EINVAL;
@@ -346,7 +344,7 @@ char** path_strv_resolve_uniq(char **l, const char *root) {
 
 char* path_simplify_full(char *path, PathSimplifyFlags flags) {
         bool add_slash = false, keep_trailing_slash, absolute, beginning = true;
-        char *f = ASSERT_PTR(path);
+        char *f = path;
         int r;
 
         /* Removes redundant inner and trailing slashes. Also removes unnecessary dots.

src/basic/path-util.h

@@ -85,6 +85,22 @@ static inline char* path_simplify(char *path) {
         return path_simplify_full(path, 0);
 }
 
+static inline int path_simplify_alloc(const char *path, char **ret) {
+        assert(ret);
+
+        if (!path) {
+                *ret = NULL;
+                return 0;
+        }
+
+        char *t = strdup(path);
+        if (!t)
+                return -ENOMEM;
+
+        *ret = path_simplify(t);
+        return 0;
+}
+
 static inline bool path_equal_ptr(const char *a, const char *b) {
         return !!a == !!b && (!a || path_equal(a, b));
 }

src/basic/unit-name.c

@@ -389,15 +389,14 @@ int unit_name_unescape(const char *f, char **ret) {
 int unit_name_path_escape(const char *f, char **ret) {
         _cleanup_free_ char *p = NULL;
         char *s;
+        int r;
 
         assert(f);
         assert(ret);
 
-        p = strdup(f);
-        if (!p)
-                return -ENOMEM;
-
-        path_simplify(p);
+        r = path_simplify_alloc(f, &p);
+        if (r < 0)
+                return r;
 
         if (empty_or_root(p))
                 s = strdup("-");

src/basic/user-util.c

@@ -589,7 +589,6 @@ int getgroups_alloc(gid_t** gids) {
 int get_home_dir(char **ret) {
         struct passwd *p;
         const char *e;
-        char *h;
         uid_t u;
 
         assert(ret);
@@ -622,18 +621,12 @@ int get_home_dir(char **ret) {
                 return -EINVAL;
 
  found:
-        h = strdup(e);
-        if (!h)
-                return -ENOMEM;
-
-        *ret = path_simplify(h);
-        return 0;
+        return path_simplify_alloc(e, ret);
 }
 
 int get_shell(char **ret) {
         struct passwd *p;
         const char *e;
-        char *s;
         uid_t u;
 
         assert(ret);
@@ -665,12 +658,7 @@ int get_shell(char **ret) {
                 return -EINVAL;
 
  found:
-        s = strdup(e);
-        if (!s)
-                return -ENOMEM;
-
-        *ret = path_simplify(s);
-        return 0;
+        return path_simplify_alloc(e, ret);
 }
 
 int reset_uid_gid(void) {